I'm using 100% pure red grape juice in my pre- and post-workout shakes. It contains about 15 g of carbs per 100 ml, i.e. about 75 g per 0.5 l shake. I then add 20 g of dextrose to my pre-workout shake and 50 g to my post-workout shake.

Bryan mentiones high fructose corn syrup in his Eating For Size article on page 2. Since I don't know what high fructose corn syrup is I'm a bit concerned about the amount of fructose (or is it dextrose?) contained in the grape juice because I don't want an increase in insulin resistance.

Is it better to switch to some other kind of liquid, or doesn't the amount of carbs in my shakes matter that much?